Bromination Of Poly(Aryl Ether Ketone) Containing Methylphthalazinone Moieties And Preparation Of Membranes

All vanadium redox flow battery is considered as an efficient green energy store device. The membrane separates the anode and cathode electrolyte solution to avoid self-discharge, and still allows ions passing the circuit. The membrane is one of key components which play very important role in the performance of VRB. Perfluorosulfonic acid membrane such as Nafion, the representative of the commercial membrane, has been used as separators for VRB due to its good chemical stability. However, Nafion membrane suffered from the high vanadium ion permeability and very high price. In this paper, poly(aryl ether ketone) containing monomethylphthalazinone moieties (OMPPEK) and poly(aryl ether ketone ketone) containing dimethylphthalazinone moieties (DMPPEKK) were brominated, respectively. Novel ion exchange membranes were prepared, and the properties of membranes were investigated.To avoid the cancer risk during the traditional chloromethylation, a series of new polymer, OMPPEK, were synthesized via polycondensation from4-(3-methyl-4-hydroxyphenyl)-2,3-phthalazin-1-ketone and4,4’-difluorobenzophenone. DMPPEKK were synthesized via polycondensation from4-(3,5-dimethyl-4-hydroxyphenyl)-2,3-phthalazin-1-ketone,4-(4-hydroxyphenyl)-2,3-phthalazin-l-ketone, and1,4-bi(4-fluorobenzoyl) benzene. The chemical structures of polymers were characterized by1H-NMR and FT-IR. The resulting polymers were brominated with NBS as the brominating agent. Investigate the influence of NBS’s dosage, reaction time on bromination reaction by controlling the other reaction conditions. The chemical structures of brominated polymers were characterized by1H-NMR and FT-IR. The brominated OMPPEK (BOMPPEK) and brominated MPPEKK (BMPPEKK) are successful prepared.BOMPPEK membranes were prepared by solution method, and then the membranes were soaked into trimethylamine aqueous solution to produce QBOMPPEK anion exchange membranes. Current efficiency, voltage efficiency and energy efficiency of the VRB single cell with QBOMPPEK2.2anion exchange membrane is98.7%,90.7%and89.5%, respectively. A series of QBMPPEKK/SPPES blend membranes were prepared from BMPPEKK and sulfonated poly(phthalazinone ether sulfone) via solution method and followed by quaterization. The effects of content of bromomethyl groups, content of SPPES, bromomethyl conversion and evaporation time on the membrane properties and VRB single cell properties were investigated. Current efficiency, voltage efficiency and energy efficiency of VRB with QBPPEKK90/SPPES blend membrane is97.5%,89.6%, and87.4%respectively.